The long-term significance of this innovative proposal is: a) to better understand the health effects of the amount and distribution of the body s composition in normal individuals, b) to examine the influences, in association with others, that predispose individuals as children and/or adults for risk of high levels of body fatness and other cardiovascular disease (CVD) risk factors, and c) to apply new methods and statistical analysis techniques to measure and better describe these relationships. These are two general comprehensive specific aims, each encompassing a set of specific hypotheses focusing on both serial and cross-sectional data. These aims are: a) to collect and use long-term serial data from the over 850 core participants in the Fels Longitudinal Study, which began in 1929, to determine relationships among patterns of change in body composition, fat-related variables, and other risk factors for CVD during childhood, adulthood and the beginning of old age, and b) to examine associations among body composition, adipose tissue distribution, risk factors for CVD, and lifestyle variables. Through continued quantification of body fatness (using methods including anthorpometry, water and air densitometry, bioelectric impedance, and dual energy x-ray absorptiometry), evaluation of specific CVD risk factors, and investigation into the nature of the changes in, and the relationships among, these traits, the scientific knowledge in these areas will continue to be advanced. Using new and existing long-term serial data, the relationships between patterns of change in specific variables as they relate to CVD risk factors and body composition will be determined. One major strength of the study is that it allows numerous possible relationships, in both serial and cross-sectional settings, to be evaluated at varying times throughout the lifespan. Accordingly, innovative analytical approaches will be used with various hypotheses focused at differing times of life, from birth to early old age, to address the proposal s specific aims. Types of hypotheses to be considered include: Are changes in body composition related to concurrent and/or previous levels or patterns of change in maturity, leptin, physical activity, or risk factors for CVD (e.g., smoking, blood pressure, insulin, lipids/lipoproteins)? Are patterns of change in risk factors related to adipose tissue distribution? What are the relationships between the age of onset of persistent obesity and/or overweight and later levels of risk factors for CVD? What are the changes in body composition, risk factors or adipose tissue distribution during the peri-menopausal period? Are these changes affected by hormonal replacement, smoking, alcohol or level of physical activity?